Doug I've been using an automatic e-mail sorter, called POPFile, for many months and I thought I'd just about got everything working well, with something like 99.9% accuracy into 12 mailboxes. Then a certain guy from Rockwell Collins comes along and upsets the apple cart. How? He adds a PS to his message, saying "Lets see how many out of office replies I get on THIS one.....". Dang me! The system's parser interprets this as an 'out of office' message :-( And Bev's reply, to boot. Just when I thought I could automatically delete all these messages, rather than send 'em to a 'check' mailbox, you happen to prove me wrong. These two are the first false positives for weeks :-( Grrrrrrrrrr! Back to the drawing board! :-) Best regards, Brian Doug Pauls wrote: > Depends... just kidding! > **And I bet it just tickles you pink to use my favorite expression back at > me! > > "Our specifications are based on solder joint connections and the solder > specifications are not in question." What does this mean? > What solder joint requirements? > > **What, you can't read my mind? Shocking. OK, here is an example. If I > pick up a copy of IPC-A-610 (Rev C), and I go to section 12.2.2.1 Chip > Components - Rectangular or Square End Components, Side Overhang, the > target is no overhang. It becomes a defect for class 3 when overhang > exceeds 25%. Looking at the requirements for end overhang, none is > allowed. These requirements come as the result of many solder reliability > studies, and are based on the dynamics of a metallic solder joint. > > Now suppose we replace the solder material with a silver filled epoxy > adhesive. Different material, different dynamics. Should these same > solder joint requirements of 25% side overhang and 0% end overhang be > applied to the conductive adhesive joint? > > I was looking for any studies that have delved into this issue. Could I > allow more side overhang or some end overhang because I am now using a > different material with different mechanical bonding strengths and > different creep characteristics? Or, is it not as reliable as solder > (Hillman, shup up)and we should require less overhang? > > Jack Crawford, does the IPC have a specification like A-610 which addresses > the issues of electrical connection using conductive adhesives? > > > Is epoxy rigidity good or bad? Is it brittle? Is it stronger? > <grin> It depends. I think you get better mechanical strength from the > epoxy, but at the cost of reworkability. > > > Doug Pauls > Rockwell Collins > > Lets see how many out of office replies I get on THIS one..... > > > > "Bev Christian" > <[log in to unmask] To: "TechNet E-Mail Forum." <[log in to unmask]>, <[log in to unmask]> > et> cc: > Subject: RE: [TN] Adhesive strength vs. overhang > 12/09/2003 02:23 > PM > > > > > > > Doug, > Depends... just kidding! > "Our specifications are based on solder joint connections and the solder > specifications are not in question." What does this mean? > What solder joint requirements? > Is epoxy rigidity good or bad? Is it brittle? Is it stronger? > > No, I do not know of any public report of the type you are talking about. > I would expect some of the big boys have their own internal ones. > Bev Christian > Research in Motion > > > -----Original Message----- > From: Doug Pauls [mailto:[log in to unmask]] > Sent: December 9, 2003 3:14 PM > To: [log in to unmask] > Subject: [TN] Adhesive strength vs overhang > > > Good afternoon all, > > Internally, we are having discussions on the amount of allowable overhang > of passive SMT components (R and C). Our specifications are based on > solder joint connections and the solder specifications are not in question. > We have an application where a silver filled adhesive is used to make the > connection between SMT metalization and mounting pad. The solder joint > requirements were applied to these adhesive joints and I am wondering as to > the validity of this. The adhesive is epoxy based and, in my mind, more > rigid than solder. I think we are unnecessarily rejecting parts that are > acceptable. > > So, before I go off and do a complex designed experiment, I thought I would > check with the Technet crowd first. Do you know of any studies that show > the adhesive force (e.g. pull strength) vs. the degree of pad overhang? > > Doug Pauls > Rockwell Collins > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 1.8e > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 > for additional information, or contact Keach Sasamori at [log in to unmask] or > 847-509-9700 ext.5315 > ----------------------------------------------------- > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 1.8e > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 > ----------------------------------------------------- > > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------